To produce silage from grass, cut grass is often gathered to form bales and wrapped by plastic strip to ferment the grass.
U.S. Pat. No. 4,793,124 issued on Dec. 27, 1988 to Anderson discloses a bale wrapping machine which wraps bales end to end in a row while allowing the machine to move along a ground surface. Bales are received by a bale receiving support, and moved into a bale wrapping device by a ram cross bar driven by two hydraulic rams moving along the sides of the bale receiving support. The wrapped bales are moved down to a ground surface along an inclined support as they are pushed by the following bales. When a row of bales is wrapped, some wrapped bales remain in the wrapping device and on the inclined support due to lack of the following bales to push them down.
In order to empty the wrapping machine of bales, it has been proposed to move unwrapped bales through the machine until the machine becomes free of the wrapped bales, and then remove the unwrapped bales by stabbing. However, this method is labor intensive and inefficient.
Another proposed method is to use the double-acting property of the hydraulic rams. Both ends of a length of webbing are attached to the ram cross bar via the last wrapped bale through pulleys provided at the end of the inclined support so as to push the last wrapped bale down by the webbing when the ram cross bar is returned to the original position by the hydraulic rams. It is difficult and dangerous to set the webbing around the bales and the pulleys properly in the machine.
Also, proposed is use of an elongated pushing bar to push the bales through the machine, as shown in FIG. 1. The elongated pushing bar 2 has multiple pin receiving holes 4 along its length. Through one of the holes 4, a removable pin 6 is inserted to connect the pushing bar 2 to the ram cross bar a so as to be driven by the hydraulic rams 10. As the bales are pushed down, the pushing bar 2 is further pushed into the machine so that the bales 12 are pushed through the bale wrapping device 14 and down the inclined support 16. In this method, the pushing bar 2 needs to be long enough to push through the bales almost the entire length of the wrapping machine. Further, the pushing bar 2 needs to be set in a proper position without any support. It is difficult and dangerous to move around and set properly in the machine such a long bar.
Another proposed method is to provide a belt conveyer to carry the bales, as shown in U.S. Pat. No. 5,012,631 issued on May 7, 1991 to Hostetler et al. Such a belt conveyer requires sophisticated mechanisms. Further, loose grass or hay which fallen from bales may clog the belt conveyer.
It is therefore desirable to provide a reliable bale push-off device which is simple and safe to handle.